Open source advocates Monday blasted a Linux licensing scheme that The SCO Group is proposing to address alleged copyright violations in the Linux operating system.SCO CEO Darl McBride announced the licensing plan on a conference call with press and analysts earlier in the day. "SCO is prepared to offer a license for SCO's UnixWare 7.1.3 product for use in conjunction with any Linux product," he said. "This licensing format will assure that Linux users will be able to run Linux in full compliance with SCO's underlying [intellectual property] rights." SCO will begin discussing the new licensing scheme with customers this week, McBride said.Linux advocates blasted the plan."They're selling a pig in a poke," said open source advocate Bruce Perens. "I think they've made an error through overconfidence, and that error has made them liable to be sued by every person who has code in the kernel, and every company," he said.Perens and other open source advocates claim that SCO's licensing scheme appears to violate the Free Software Foundation's GNU General Public License (GPL) software license that governs Linux."It's very definitely in violation of the GPL," said Perens, who believes that SCO's terms would place restrictions on Linux users' ability to modify and redistribute source code, making it at odds with the GPL. "We do not authorize our code to be used under the terms of the SCO license; it's very plain in the GPL," he said.An independent intellectual property lawyer observing the lawsuit said that Perens' contention had merit. "I think that's a good argument," said Jim LaBarre, a partner with Burns, Doane, Swecker & Mathis LLP, a law firm in Alexandria, Va. "On its face it sounds like that's a plausible argument," he said.SCO disagreed, saying that its new license, which has yet to be publicly revealed, will not conflict with GPL.The Linux source code has been under attack from SCO, of Lindon, Utah, for months now. In March, the company sued IBM for $1 billion, claiming that Big Blue had harmed SCO's market for Intel-based Unix operating systems by improperly adding code to the Linux kernel, the software program at the center of the Linux operating system.At the time, SCO claimed its dispute was with IBM and not the Linux community, but it has gradually set its sights on Linux users as well. In May, SCO sent letters to 1,500 companies warning them that they could be held liable for IP violations in Linux, and on Monday SCO's attorney David Boies, of the firm Boies, Schiller & Flexner LLP, said that there was a possibility that SCO could pursue case-by-case litigation against companies that used Linux.SCO's McBride declined to say exactly what SCO's licensing plan would cost, but he said it would be a per-processor license, with volume discounts available for some customers.The licensing plan would not only be in violation of the GPL, but also completely pointless, according to Free Software Foundation General Counsel Eben Moglen. "You don't need a copyright license from anybody to use any program," he said. "that's like saying you need a copyright license to read a newspaper... if there's plagiarized material in the New York Times, that doesn't mean that people who buy the New York Times are liable."A copyright license is required to redistribute software, Moglen said, but Linux distributors will not be able to adopt the SCO license because it would place them in conflict with the GPL, he said.Linux distributor Red Hat, for one, had no interest in adopting SCO's license. "We have full confidence in our code, so we don't feel this license is necessary for anybody," Red Hat spokeswoman Leigh Day said. "It's just another tactic in this battle that they've waged through the media. It's just a distraction," she said.Talk of licensing SCO's code is premature, given that the company has yet to publicly identify where the alleged violations of its copyright occur, Linux vendors said."SCO has not shown us any code contributed to Linux by IBM which violates SCO copyrights," IBM spokeswoman Trink Guarino said. "SCO needs to openly show the Linux community any copyrighted Unix code which they claim is in Linux. SCO seems to be asking customers to pay for a license based on allegations, not facts," she said.SCO also announced on Monday that it had received U.S. copyright registration for its Unix source code, a move that observers say is a necessary precursor to any copyright-based litigation.